In a startling shift, the state Department of Transportation is putting the brakes on the I-84 viaduct replacement project in Hartford and plans to broaden the scope of its study to better coordinate with other transportation projects in the Hartford area. The $5 billion viaduct replacement is still on the table, but DOT planners say the study now also will give more emphasis to options for travel by rail, the CTfastrak busway and bicycle. Travel alternatives to motor vehicles are seen as one way to ease congestion on the state’s highways. The change in scope also comes as the administration of Gov. Ned Lamont has made relieving highway congestion a pillar of its transportation improvement plans.